With the fast development of display technology, touch display panels have gradually become popular in people's life. At present, according to constitution structure, touch screens may be classified into add-on mode touch panels, on-cell touch panels and in-cell touch panels. For an add-on mode touch panel, the touch panel and the liquid crystal display (LCD) are produced separately and then attached together to form a liquid crystal display with touch function. Add-on mode touch panels suffer disadvantages such as high manufacturing cost, low light transmission rate and a big assembly thickness. For an in-cell touch panel, touch electrodes of the touch panel are embedded inside the liquid crystal display, which can reduce the overall thickness of the assembly, and can drastically reduce manufacturing cost of the touch panel. Therefore, in-cell touch panels have received more attention from panel manufacturers.
At present, an in-cell touch panel detects the touch position of a finger in accordance with the mutual capacitance or self-capacitance principle. For the self-capacitance principle, it is possible to provide a plurality of self-capacitance electrodes that are disposed in the same layer and insulated from each other in the touch panel. When a human body does not touch the screen, each self-capacitance electrode experiences a capacitance of fixed value. When the human body touches the screen, corresponding self-capacitance electrodes experience capacitance that is the fixed value plus the body capacitance. The touch sensing chip can determine the touch position by detecting capacitance value variation of self-capacitance electrodes in the touch period. Since the body capacitance can act on all the self-capacitances, as compared to the fact that the body capacity can only act on projection capacitance in mutual capacitance principle, the touch variation caused by the body touching the screen is greater than that of the touch panel manufactured in mutual capacitance principle. Therefore, as compared to touch panels utilizing the mutual capacitance principle, touch panels utilizing self-capacitance principle can effectively increase signal-to-noise ratio of the touch and thereby improve accuracy of touch sensing.
While designing a touch panel in the self-capacitance principle, each self-capacitance electrode is connected with the touch sensing chip via a separate lead-out wire. As shown in FIG. 1, for example, each lead-out wire comprises: a wire 2 for connecting a self-capacitance electrode 1 to the margin frame of the touch panel, and a periphery wiring 4 disposed in margin frame for connecting the self-capacitance electrode 1 to a connecting terminal 3 of a touch sensing chip.